deref in a string into an operand

[John Doe]

I've got the action '+' stored as the variable 'plus',
that is plus='+'

Now I want to use the variable plus in an equation:
5 plus 7, just line 5 + 7

How do I do that?

Dan

[John Doe]

Foolish me; I examined the __builtin__ and found __getattribute_ _,
along with '__mul__' '__add__', '__sub__' and '__div__'.

So using a builtin object like 'x' ...

x = 5
attr = '__mul__'

print x.__getattribut e__( attr )( 5 )
25

My program will store the operand as '__mul__' instead of '*', along with
a health bit of comment.

Dan. Closed.

On Fri, 05 Nov 2004 08:01:59 +0000, John Doe wrote:

I've got the action '+' stored as the variable 'plus',
that is plus='+'

Now I want to use the variable plus in an equation:
5 plus 7, just line 5 + 7

How do I do that?

Dan

[Peter Otten]

John Doe wrote:

Foolish me; I examined the __builtin__ and found __getattribute_ _,
along with '__mul__' '__add__', '__sub__' and '__div__'.

So using a builtin object like 'x' ...

x = 5
attr = '__mul__'

print x.__getattribut e__( attr )( 5 )
25

My program will store the operand as '__mul__' instead of '*', along with
a health bit of comment.

However, this may sometimes fail:

1 + 1.0 2.0 1 .__add__(1.0) NotImplemented

Consider using the operator module instead:
import operator
operator.add(1, 1.0) 2.0 getattr(operato r, "add")(1, 1.0)

2.0

Peter

[Steven Bethard]

John Doe <atterdan <at> yahoo.com> writes:

So using a builtin object like 'x' ...

x = 5
attr = '__mul__'

print x.__getattribut e__( attr )( 5 )
25

My program will store the operand as '__mul__' instead of '*', along with
a health bit of comment.

You also might consider just storing the operator.<op> methods in an appropriate
dictionary:

import operator
operator_map = {'+':operator.a dd, '-':operator.sub}
operator_map['+'](1, 2.0)

3.0

This allows you to call the add function whatever you want.

Steve

[Peter Abel]

John Doe <at******@yahoo .com> wrote in message news:<pa******* *************** ******@yahoo.co m>...

I've got the action '+' stored as the variable 'plus',
that is plus='+'

Now I want to use the variable plus in an equation:
5 plus 7, just line 5 + 7

How do I do that?

Dan

If you want a string:
equation = '5 '+plus+' 7'

or

equation = '5 %s 7' % plus

Regards
Peter